Electron discharge device



June 11', 1935 w. HEHLGANS I 2,004,790

Y ELECTRON DI SC HARGE V DEVICE Filed May 11, 1933 1 Friedrich WHehlgan's;

His Attor-neg.

a to thecontrol electrodeor Wehne'lt cylinder of a cathode-ray tube, asusedpfor sound. recording,

Patented June 11, 1935 i H ehlg ans, Berlin-Hermsdorf, Ger-'many,jassignor to GeneralElectric Company, a

corporation of New York I fln lication May 11,1933,"SerialNo."670,556

- The invention relates :to neared n discharge devices, suchascathode-raytubes,- employed for the purposes-of sound recording,televisionyetc;

An object or the present invention is to provide f a circuit arrangementand apparatus for increas ing by regenerative action, the electricalimpulses i applied to the cathode-.rayt'ube whereby the light output andcontrol of the tubeare enhanced.

The invention is ,based on thefollowing p1in-- ciple: If alternating:current voltagesare applied and a telephone receiveris connected in theanode circuit of the tube, electric impulses of considerable strengtharefound :to exist inthe anode circuit; These impulsesrepresent afaithfulreproduction, in amplifiediorm, of the voltages applied to thecontrol cylinder; I i i I I, In accordance with .thepresent invention;this principle is employed for increasing the-light output of thecathoderay tube in suchxa manner that theoscillations occurring in theanode cir-' cuit of the tube are appliedtothe control circuit of. thetube in such phase as toradd'to the original alternating currentvoltage. 'I'heinventi'on Will be better understood when reierenceflismade to thefollowing description and. the accompany-- ing drawing inwhich Fig.1 shows diagrammati c'ally'a, system embodyingthe inventionand-Fig. 2

illustrates an alternative arrangement a In Fig. 1, numeral l designatesa: microphone transmitter connectedin'serieswith an ei'iergiz'ingbattery 2 ,andthe primary ofgatraLnsformert. The secondaryiwoi the.transformer is connected to theinput circuit of a thermionic amplifier 4of ordinary construction; amplifier includes an electrostatic controlmember 5, a filamentary cathode 6 and an anode I. The filament and theanode are connected to difierent potential taps on a common battery 8 orother source of potential. The control member 5 is connected to thenegative end of the battery in such a manner as to obtain a constantnegative bias.

The output circuit of the amplifier 4 is connected to the controlcircuit of a cathode-ray tube 9 by means of a well-known capacity andresistance coupling consisting of a capacitor 1' and resistances II andI2. If desired, an inductive or transformer coupling may beused.

The cathode-ray tube is of ordinary type and includes a cathode IS, acontrol electrode or Wehnelt cylinder 14 and an anode l5 in the form A01' a circular plate of metal provided with a central aperture It forthe cathode rays. At the end of the envelope, opposite from the cathode,there rmlnGermanyi May 2?, 1932 r r m ns (0 173-4 0 is a screen I! ofwell-known form which fluoresceswhen struck by electrons and the lighttherefrom isradiated onto a movingfilm 18. The cathode 13, "controlmember I4 and 'the anode iii of the c'athoderay tubeare connected tovarious potentialtaps on the common battery 8. Asin the case of'theamplifier" 4, the control member of the resistance [9.

The purpose of the cathode r'ay tube is to translate theelectricalundulations applied to the cylinder 14 into light images Whichare photographical-1yreproduced-on the sound'recordl8.

1 -Inacc0rdance with my invention, a regenerative circuit isprovidedbetween the anodeand control electrode circuits of the cathode-ray tubeorderto increase the control exercised by the cylinder M'on the electronbeam striking the fluorescent'screen-H; increased control of theintensity of the light spotand of the photographic image on thesoundtrack l8'is obtained.

As shown in Fig. Lthis regenerative effect is produced bymeansof aback-coupling through a conductor 20 connected to a point in-the'anodecircuit between the anode 15* and the resistance l9. This conductor hasin series therewitha capacitor 2}, fixed or adjustable, also aresistance 22: whichis connected to a point between the secondarywinding of the transformer: Send an adjustable resistance 23 inserted inthe control circuit of the amplifier 4. The relative magnitude of theresistances 22 and 23 determines the voltageincrement which is appliedto the input of the amplifier 4 and hence, provides an adjustment of theincreased voltage impressed on the control member of the cathode-raytube. It is apparent that by reason of the introduction of the amplifierbetween the source of voltage variations and the control member of thecathoderay tube the energy fed back in this manner is in the propervoltage phase relation with respect to the voltages applied to theamplifier 4 so that an amplification of these voltages and thereforeelectrode may be formed for example as a grid,

additional amplifier 4. In this case, an additional electrode may bearranged between the cathode and the Wehnelt cylinder of the cathode-raytube and the regenerative voltage taken from the circuit which includesthis auxiliary electrode. The

or plate with a central opening and is positively charged. Fig. 2 showssuch 'a system. v L V As illustrated in Fig. 2, the microphonetransmitter l is connected in the local circuit and pro:

ment or Wehnelt cylinder I4 and=thecathode 13 on their way to thefluorescent screen I I.

Between the cathode andtheicontrol cylinder,

there is an electrode 24 having a central aperture 25 in line with theopening in the cylinder 4, and the aperture IS in the anode Hi. Theelectrode 24 is connected through the current-limiting resistance 26 toan intermediate positive terminal on'the common battery or sourceofenergy supply 8. A regenerative coupling is connected between theelectrode M and the inputcircuit 0f the cathode-ray tube through acapacitor 2| and resistance 22. It is apparent that instead of thecapacitor 2|, an inductive coupling may be used but the capacitycoupling is preferred since it is more free from resonance efiects, andselfexcitation within the cathode-ray tubeis thereby avoided. However,if the capacitor 2 l 1 is replacedby an inductive coupling, theproduction of selfsustained oscillations may be substantially reduced bya Proper adjustment of the resistances 22, 23 and the proper choice ofthe: voltages employed in the system. y a

'What I claim as new and desire to-secure by Letters Patent of theUnited States, is:,

1. In combination, a cathode-ray tube for translating electricalimpulses into light rays, said tube including a cathode, an anode, anelectrostatic control member and a screen adapted to fluoresce' whenstruck by electrons, energy supply circuits for. the electrodes, asource" ofyelectrical impulses connected to said control member, andmeans for transferring electrical energy from the anode of said tube tothe control member, said meansincluding an electrical coupling vbetweensaid anode and control member, whereby control of the electrons throughthe tube and the variations in intensity of the light spot' on thefluorescent screen are enhanced.

,2. In combination, a cathode-ray tube for translating electricalimpulses into light rays, said tube including a cathode, an anodaanelectrostatic control member and a screen adapted to fluoresce whenstruck by electrons, energy supply circuits for the electrodes,-a sourceof electrical impulses, an amplifier having input and outputcircuits,'said input circuit being connected to said source of impulses,said output circuit being connected to said control member, and anelectrical. energy v; feedback connection ;between said anode an'dtheinput circuit of'said ampli- .fier for increasing the control exercisedon the duces voltage variations between the control eleelectron streamin the cathode-ray tube by said control member and for enhancing'thevariations in the intensity ,of the luminous spot produced on the screenby electrons; I

3. In combination, a cathode-ray tube for translating electricalimpulses into light rays,

said tubeinoluding a cathode, an anode, an electrostatic control memberand a screen adapted to fluoresce when struck by electrons, energysupply circuits for the electrodes, a source of electrical impulses', anamplifier having input and output circuits, said input circuit beingconnected to said source of'impulses, said' output circuit beingconnected .to said control member, and an electrical energy feedbackconnection between said anode and the input circuit of said amplifier,said connection includinga capacitor.

4. In' combination, a cathode-ray tube 'for translating electricalimpulses into light rays, said tube including a cathode, an anode, anelectrostatic control member,ienergy supply circuits for the electrodes,said tube also containing a screen which fluoresces when struckbyelectrons and an electrode positioned between said control member andthe cathode and adapted to be charged positive with respect to thecathode, and an electrical energy feedback connection between saidpositively charged electrode'and said control memberxwhereby.the.'control of the position and the variations in intensity of. theluminous spotproduced on the screen by electrons are enhanced. I

5.-In combination, a cathode-ray tube for translating electricalimpulses "into light rays,

said tube including a cathode, an anode, an'electrostatic controlmember, energy supply circuits for the. electrodes, said' tube alsocontaining a screen which fluoresces when struck by electrons FRIEDRICHW. HEHLGANS.

